Quantum Mechanics 2

Normal Modes of Vibration of a String

3-dimensional modes of vibration (shown in 2 dimensions!)

The Exclusion Principle Two fermions of the same type cannot occupy the same quantum state at the same time It also keeps particles from being packed too closely together, such as in the nucleus. Bosons (for example, photons) do not obey the exclusion principle.

Thermal Pressure Thermal pressure changes with temperature (Hence the name!)

This pressure supports stars that have fusion going on in their core against gravity. Energy from the fusion keeps the gas hot. Thermal Pressure

But we compress a plasma, it heats up. Let it cool, and we can compress it some more. We can do this over and over, but not forever. There is a limit. The Exclusion Principle won’t allow the electrons to get into the same state. It pushes back with a “degeneracy pressure”. Degeneracy pressure does NOT depend on temperature.

White dwarfs and brown dwarfs are held up against gravity by electron degeneracy pressure

An electron in an atom… a)can be modeled as a standing wave or vibration. b)can create quantization in different harmonics. c)are found in orbitals. d)all of the above e)Only A and C

Two fermions (such as electrons, protons, neutrons) … a)attract each other if they get close enough. b)can't be in the same atomic energy level. c)can't be in the same quantum state. d)all of the above e)none of the above

If the dead star has too much mass, electron degeneracy can’t hold up against gravity As the electrons are pushed closer together, they must move faster (Uncertainty Principle) When their speed approaches the speed of light, the star collapses into a ball of neutrons. A neutron star is held up by neutron degeneracy pressure. Turns out there’s a limit to that, too.

Quantum tunneling is an effect of the uncertainty principle Without it, there would be no fusion inside stars. No starlight, no life!

Macroscopic tunneling doesn’t happen – probability is MUCH to low.

Black Holes evaporate!

Astro-Cash Cab! Alejandro Adrianna Mariah Derek

1) If you try and compress (or confine) the electrons in atoms too much, a)they have a pressure that resists. b)two electrons can merge together. c)degeneracy pressure can oppose further compression. d)all of the above e)A and C

2) Virtual particles can come into existence because of the Uncertainty Principle the Exclusion Principle Quantum Tunneling

3) True or False? Degeneracy pressure increases as the plasma gets hotter.

4) Which type of particle obeys the Exclusion Principle? Bosons Fermions All particles